Early Glottic Cancer: Surgery or Radiation Therapy?

Radical radiotherapy for early glottic cancer: Results in a series of 1087 patients from two Italian radiation oncology centers. I. The case of T1N0 disease

PURPOSE

To retrospectively evaluate local control rates, late damage incidence, functional results, and second tumor occurrence according to the different patient, tumor, and treatment features in a large bi-institutional series of T1 glottic cancer.

METHODS AND MATERIALS

A total of 831 T1 glottic cancer cases treated consecutively with radical intent at the Florence University Radiation Oncology Department (FLO) and at the Radiation Oncology Department of the University of Brescia-Istituto del Radio "O. Alberti" (BS) were studied. Actuarial cumulative local control probability (LC), disease-specific (DSS), and overall survival (OS) rates have been calculated and compared in the different clinical and therapeutic subgroups with both univariate and multivariate analysis. Types of relapse and their surgical salvage have been evaluated, along with the functional results of treatment. Late damage incidence and second tumor cumulative probability (STP) have been also calculated.

RESULTS

In the entire series, 3-, 5-, and 10-year OS was equal to 86%, 77%, and 57%, respectively. Corresponding values for LC were 86%, 84%, and 83% and for DSS 96%, 95%, and 93%, taking into account surgical salvage of relapsed cases. Eighty-seven percent of the patients were cured with function preserved. Main determinants of a worse LC at univariate analysis were: male gender, earlier treatment period, larger tumor extent, anterior commissure involvement, and the use of Cobalt 60. At multivariate analysis, only gender, tumor extent, anterior commissure involvement, and beam type retained statistical significance. Higher total doses and larger field sizes are significantly related (logistic regression) with a higher late damage incidence. Scatterplot analysis of various combinations of field dimensions and total dose showed that field dimensions >35 and <49 cm2, together with doses of >65 Gy, offer the best local control results together with an acceptably low late damage incidence. Twenty-year STP was equal to 23%, with second tumor deaths being more frequent than larynx cancer deaths (67 of 831 vs. 46/831).

CONCLUSION

The results of this study support the opinion, suggested by some international guidelines, that radiotherapy is standard treatment for T1 glottic cancer. Better results are obtained in patients with less extended disease and with 4-6 MV photon beams. The use of doses in excess of 65 Gy and of field sizes of 36-49 cm2 is probably the best technical choice available. Late damage is infrequent, but careful follow-up is warranted to detect early not only relapses (because conservative salvage surgery is feasible), but also second malignant tumors, which constitute the main cause of death in these patients and are potentially curable.

Causes of failure of curative radiation therapy in 205 early glottic cancers

A retrospective analysis of the results obtained with curative radiation therapy in a series of 205 patients affected by early glottic cancer treated from 1970 to 1985 at the Florence University and Hospital Departments of Radiotherapy is presented. All patients were staged according to TNM System (UICC 1978) as T1-T2 NO. The overall 5-year local control rates were 88% for T1a, 75% for T1b, and 64 for T2. The main cause of failure was progression or recurrence in T (41/48); five failures were observed in T and N at the same time and two in N. Of these 48 patients, 21 (44%) were salvaged with surgery. After surgical salvage of radiation failures, the 5-year survival rates were 95%, 91%, and 73%, respectively, for T1a, T1b, and T2. The extent of T and the number of subsites involved significantly affected local control. Vocal cord mobility was less important. The incidence of failures and damages was analyzed according to the radiation beam, the size of the irradiated volume, fractionation, and total tumor dose.

Radiotherapy or surgery for T2N0M0 glottic carcinoma? A decision-analytic approach

Decision analysis was used to evaluate the results of treatment of T2N0M0 glottic carcinoma as presented in the literature. Based on mean values for recurrence, salvage eligibility after recurrence and salvage success, the 5-year survival after radiotherapy and surgery proved to be almost identical, 85 and 86%. If the recurrence rates and the salvage rates were varied, a marginal advantage for surgery in small tumours (T2a) and a major advantage in more extended (T2b) tumours was seen if only survival is considered. To take the quality of speech into account, a utility analysis was performed. A utility scale was defined ranging from 0.0 as the value for death, to 1.0 for a successfully irradiated patient with preservation of normal speech. A utility of 0.99 or less for the laryngectomized patient would favour radiotherapy over surgery for all T2 tumours. In patients with T2b tumours and in extreme circumstances, e.g. if failure rates of radiotherapy are extremely high or if recurrence rates after surgery are extremely low, an exact assessment of patient utilities may be pivotal. Under normal circumstances radiotherapy is preferred for T2N0M0 glottic carcinoma if both survival and the quality of speech are taken into account.